Formation of wrap-around-edge tab handle



Dec. 24, 1968 w. T. SAUNDERS 394179595 FORMATION OF WRAP'AROUND-EDGE TAB HANDLE Filed May 3, 1966 PRIOR ART IK W 8 FIG. 3 HG.

4 2s 32 /3s 32 1 30 J INVENTOR.

WILLIAM T. SAUNDERS United States Patent 3,417,595 FORMATION OF WRAP-AROUND-EDGE TAB HANDLE William T. Saunders, Weirton, W. Va., assignor to National Steel Corporation, a corporation of Delaware Filed May 3, 1966, Ser. No. 547,211 1 Claim. (Cl. 72-354) ABSTRACT OF THE DISCLOSURE Single stroke method for curling the edge of a sheet metal blank having a cup-like cross-sectional configuration in which the base section of the sheet metal is supported by fixed die means and the sidewall portion is held in position for curling by yieldably mounted die means. The yieldably mounted die means support the sidewall while a movable punch with curling contour contacts the sidewall portion. During the curling portion of the stroke the yieldably mounted die means is moved by the movable punch means.

This invention is concerned with formation of a wraparound-edge tab handle from a sheet metal blank.

Tab handles for easy-open sheet metal containers are ordinarily made from sheet metal of equal or greater strength than the sheet metal of the container. Since these containers are opened by hand, the sheet metal forming the handles must be wrapped around on the edges in order to avoid sharp cutting edges.

The present invention provides a single stroke, low cost, high yield production method of making wraparound-edges on sheet metal blanks.

The accompanying drawings Will be used for explaining the present invention and presenting features which distinguish the invention over the prior art. In the drawings:

FIGURE 1 is a schematic cross-sectional view of apparatus used in the prior art for curling a sheet metal edge,

FIGURE 2 is a schematic cross-sectional view of apparatus for carrying out the present invention with such apparatus positioned at the start of its single working stroke,

FIGURE 3 shows the apparatus of FIGURE 2 positioned approximately at middle of its working stroke, and

FIGURE 4 is a further view of the apparatus of FIG- URE 2 shown at the completion of its working stroke.

Metal for a tab handle is ordinarily cut or blanked from sheets to roughly the desired final shape of the handle and then edge portions of the blank are wiped down so as to extend perpendicularly from the remainder of the blank. The result is a metal blank having a cup-like configuration in cross section as shown at 12 in FIGURE 1. The cup-like metal blank includes a body or base section 14 and sidewall metal 16 which is substantially perpendicular to the plane of base section 14.

In order to convert the metal blank into a tab handle it is necessary to curl the sidewall metal inwardly and downwardly to form a wrap-around-edge and conceal the raw edge 18 of the sheet metal blank. A die, such as 20, with a curling contour 22 is provided for forming the wraparound-edge.

However, in the prior art practice, before this curling operation could begin, it was necessary to perform a coaxing step on the sidewall metal 12. The result of this coaxing step is shown in dotted lines in FIGURE 1. The sidewall metal 12 had to be bent inwardly to establish proper relationship with curling contour 22 before the 3,417,595 Patented Dec. 24, 1968 start of a stroke. Coaxing side metal required a separate stroke using forming means which bent the sidewall metal to the desired angle. Unless bent to the proper angle, the following stroke of curling die 20 would flatten the side metal rather than form a wrap-around-edge. Tab handles must be produced rapidly and with a high useful percentage yield to meet economic requirements. The 2-stroke method of the prior art slowed production and caused high production costs.

The present invention avoids such problems of the prior art by providing a high production rate, low cost, single stroke method for producing Wrap-around-edge sheet metal tab handles.

The metal blank 24, shown in FIGURE 2, has sidewall metal 26 which is substantially perpendicular to the base section 28. With the present invention no coaxing step is required prior to curling the edge metal and no losses due to flattening of edge metal is experienced.

In carrying out the invention the base section 28 of sheet metal blank 34 is rigidly supported on fixed die 30. Exterior to the fixed die 30, and in surrounding relationship to sidewall metal 26, is a yieldably mounted die 32. As shown in the specific embodiment, die 32 can be mounted with springs which are compressed by downward movement of die 32 and which, upon expansion, move die 32 upwardly. While spring mounting has a number of advantages due to its simplicity, die 32 can be yieldably mounted using hydraulic, pneumatic or other suitable means.

Sheet metal blank 24 is supported as shown in FIG- URE 2 at the start of aworking stroke. Punch 36 includes surface 38 for contacting movable die 32 and an edge curling contour 40. Punch 36 is movable along a path perpendicular to base section 28.

With yieldably mounted die 32 supporting sidewall metal 26, punch 36 is moved downwardly. Die 32 is moved downwardly by punch 36 but continues to support sidewall metal 26 and prevent outward movement of sidewall metal 26 which would increase the angle between base 28 and sidewall metal 26. During downward movement of punch 36, sidewall metal 26 is guided into curling contour 40 as shown in FIGURE 3.

FIGURE 4 shows the completed stroke in forming a wrap-around-edge. Yieldably mounted die 32 has been moved downwardly out of contact with the sheet metal blank and the sidewall metal 26 has been bent so as to conceal raw edge 44. With these teachings, wrap-aroundedges can be produced in a single stroke at production rates for exceeding those of the prior art.

Formation of the described die parts and operation in conventional'die machinery is within the skill of those having experience in the art. The invention can be used with any of the conventional container metals and is to be limited only by scope of the appended claim.

What is claimed is:

1. A single stroke method for forming a wrap-aroundedge tab handle for an easy-open container from a sheet metal blank having a cup-like cross-sectional configuration with a base section and sidewall metal extending substantially perpendicularly from the base section comprising. the steps of rigidly supporting the base section of the metal blank on fixed die means,

positioning yieldably-mounted die means in surrounding relationship to the sidewall metal of the metal blank to provide lateral support for and prevent outward movement of the sidewall metal during formation of the sidewall metal into a wrap-around edge, providing a movable punch means capable of movement in a direction substantially perpendicular to the base section, the movable punch means including References Cited a surface for contacting the yieldablY-mounted die UNITED STATES PATENTS means and a curling contour for receiving the sidewall metal of the blank and Muelller moving the punch means into contact with the yield- 5 1,581,680 4/1926 f 72354 ably-mounted die means and the curling contour into 2,227,524 1/1941 Wlnmms 72*355 contact with the sidewall metal, with the yieldably- 25081953 1/1943 P Y 72'354 X mounted die means supporting the sidewall metal 2,119,630 6/1938 Wllhams 72'-358 X during movement of the punch means and preventing outward movement as the sidewall metal is curled 10 MILTON MEHR Examiner toward the base section forming a wrap-around-edge US. Cl. X.R.

tab handle from the sheet metal blank. l13-121 

